The bar is high for bad comedies, but "The Watch" promises to be this summer's worst. It's a muddled, jumbled scrapbook of a film that is bafflingly uncertain of what it is trying to be funny about. There is a cast of oblivious imbeciles, gross-out misbehavior, crass bedroom farce, and a science fantasy twist whose stupefying silliness is almost, but not quite, comic. It lurches from scene to dismal, rhythm-less, momentum-killing scene, tripping over its contradictions every step of the way.

Ben Stiller, Vince Vaughn, Jonah Hill and English TV comic Richard Ayoade play everyday guys who band together to patrol the streets of their town following a ghastly murder. That garishly visualized "comic" killing is just the first in a cascade of tonally jarring, badly judged routines. Stiller's character is the straight man, the wonkish manager of a big-box store who recruits volunteer investigators after the freakish death of his night security officer. His call to arms enlists three oddballs. Hill plays a loony-violent police academy washout looking for a chance to one-up the local cops and break some heads in the bargain. Vaughn is a jabber-jawed party animal who sees the team as drinking buddies, and Ayoade ... well, he's not asked to do much except be quirky and English.

The script, written in part by Seth Rogen and Evan Goldberg, who scored with "Superbad" and "Pineapple Express," feels strained and dashed-off. The plot's big surprise is a twist straight out of "The X Files."

Yet when the four stooges realize what they're up against, they unaccountably keep the earth-shattering news to themselves. While these squabbling goofballs have uncovered a threat that could mean planetary extinction, they're more interested in interpersonal psychodramas and petty animosities.

The otherworldly menace offers director Akiva Schaffer the opportunity to send chunks of flesh flying for comedic effect. In steadier hands, the spectacle of steaming intestines might have yielded riotous Grand Guignol. Charlie Chaplin has been quoted as saying, "Life is a tragedy when seen in close-up, but a comedy in long-shot." Schaffer, clueless about (or uninterested in, or incapable of) finding the proper point of view, shows the splatter up close and for too long, killing the joke.

There were flickers of promise in the film. Stiller is playing yet another soulful, maladroit sad sack, but I liked Hill's character, a big baby faking macho swagger to keep from looking vulnerable, and Vaughn's working-class thugishness. Alas, they never attain takeoff velocity.

I hoped the verbal riffing among the four leads would produce a dizzying pile of absurdities. Instead it plays like outtakes where they're filling time with any notion that pops into their heads.

"Saturday Night Live's" Will Forte brings crack timing and switchblade sarcasm to the small role of an antagonistic cop, and Billy Crudup does a shrewd turn as an eerily placid new neighbor. In the midst of this cartoonish, boring, almost completely terrible movie, they gave me fits of giggles. Maybe there's a buddy cops vehicle for them out there somewhere?